Filter device

ABSTRACT

A gas filtering device in which a series of filter units are arranged parallely within a housing. Each filter unit comprises a frame about which fabric filter is wrapped to form parallel sides, thereby providing a filter pocket. The filter units are inserted into a casing through slots in a casing wall. The free edge of the filter fabric is wound around a sealing ring so as to form a welt. A sheet metal cover strip closes the open front side of each frame, clamps the welt against the casing wall at the slot edges, and this cover has a tubular connector disposed outside of the housing and affording sole access to the filter pocket.

States atent [191 FILTER DEVICE Gert Wolfgang Kroll, 18 Bayemstrasse,Hosel near Dusseldorf, Germany Filed: Apr. 30, 1973 Appl, No.: 355,451

Related [1.8. Application Data Continuation-in-part of Ser. No. 77,651,Oct. 2, 1970, abandoned.

Inventor:

us. c1. .Q. 55/341, 55/379 Int. Cl. B01d 46/02 Field of Search 55/341,379, 302

References Cited UNITED STATES PATENTS 4/1968 Young 55/302 1/1969 Swiftet a1 55/341 [4 1 Feb. 12, 1974 Primary Examiner-Bemard Nozick Attorney,Agent, or FirmMalcolm W. Fraser [5 7] ABSTRACT A gas filtering device inwhich a series of filter units are arranged parallely within a housing.Each filter unit comprises a frame about which fabric filter is wrappedto form parallel sides, thereby providing a lilter pocket. The filterunits are inserted into a casing through slots in a casing wall. Thefree edge of the filter fabric is wound around a sealing ring so as toform a welt. A sheet metal cover strip closes the open front side ofeach frame, clamps the welt against the casing wall at the slot edges,and this cover has a tubular connector disposed outside of the housingand affording sole access to the filter pocket.

3 Claims, 3 Drawing Figures PATENTEDFEBJ 2 1974 SHEEI 1 BF 2 mmlPAIENTEH FEB 1 2 I974 SHEET E OF 2 QBQBBEQ W 8 IIII I I FILTER DEVICERELATED APPLICATION FIELD OF INVENTION Gas Separation, Two or MoreSeparators, Spaced for parallel flow of gas.

PRIOR ART Young US. Pat. No. 3,377,783; Swift et al. U.S. Pat. No.3,421,295; Byers U.S. Pat. No. 3,590,562

BACKGROUND OF THE INVENTION The invention relates to a filtering devicehaving several filter pockets, each consisting of a frame covered withfilter material separating the soiled gas side from the pure gas side,and to which scavenging air may be applied for cleaning of the filterpockets.

The effective operation of such pocket filters is dependent to a highdegree on the regular cleaning of the filter materials. The connectionof the scavenging air necessary therefor must on the one hand functionreliably, and on the other hand must require no excessive expenditure.

It is known in pocket filters to combine several filter pockets in onefilter chamber, on whose pure gas side a valve arrangement is providedwith which the cleaning air may be connected. With such a pocket filter,the clean gas chamber is relatively large. That is in itself ahindrance. In addition, however, the packings of the filters lie in thepure gas chamber, so that in the per formance of the filter, infiltratedair or in case of nontightness of the pocket seal, also dirty air may besucked in. Therefor, for a particularly reliable seal, care must betaken to this end, and this is expensive. Finally, the individual filterpockets of a chamber may be handled and serviced with difficulty,particularly since their installation and removal involve difficulties,as well as the subsequent covering of the filter cloth.

SUMMARY OF THE INVENTION vention is to overcome by means of a change inthe clean gas side, particularly the disadvantages of the pocket filtersdescribed in the foregoing.

By means of the invention, the clean gas chamber is practicallyrestricted to the volume of the frame spanned by the filter material.The sealing of the filter cloth extends out of the clean gas chamber. Inaddition, each filter pocket remains accessible from the outside and mayalso be cleaned individually with scavenging air.

Countless advantages result therefrom: The problems of sealing thefilter pockets are greatly reduced. The sucking in of infiltrated airis, therefore, reduced or prevented by simple means. Beyond this, evenupon non-perviousness of the pocket seal, no soiled air is sucked intothe clean gas chamber. The retightening of the insertion or installationand removal of filter pockets as Well as other maintenance work requiresubstantially less expenditure than formerly. Furthermore, the decreaseaccording to volume of the clean gas chamber contributes altogether to amore compact type of construction of the pocket filter.

For the fastening of the filter pockets to the open front side of theframe, sheet metal covers, each having a pipe directed outwardly, areemployed for attachment to a tube leading to the cleaning device.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation, partlybroken away to show the interior, of the filtering device;

FIG. 1A is an enlarged fragmentary detail of the portions of thefiltering device shown in the upper righthand corner of FIG. 1; and

FIG. 2 is a front elevation of the filtering device, partly broken away.

Referring now to the drawings in which like reference numerals denotesimilar elements, the filtering device 2 comprises a sheet metal case 4mounted on a frame 6 which is supported above floor 8 by legs 10.Extending across the rear portion of the top wall 12 of the casing is aduct 13 which is open at one end for connection witha source of dustladen air, generally at below atmospheric pressure. Depending from thebottom of the casing is a funnel-shaped hopper 14 into which the dustfalls. Across the front of the casing are a series of nozzles 16 throughwhich the clean filtered air passes. The nozzles 16 are part of metalstrips 32 which are clamped to the front side of the casing 4. The cleanair duct to which the" nozzles are connected is generally at reducedpressure. For purging the filtering device, the nozzles 16 are connectedto conventional hoses which, in turn, may be connected to a suitablepurging device, by means of which back-pressure air is fed sequentiallythrough individual ones of nozzles 16 into the individualfiltering unitswithin casing 4, which are described hereinafter, so that the exteriorsof the filter bags of these units can be purged of dust collectedthereon.

Within casing 4 are a plurality of filter pockets 18 each formed by afabric filter bag 20 stretched over a U-frame 22, which, in thisexample, is a tube. The filter bags are individually insertable into andremovable from casing 4 through vertical slots in the front wall 24 ofcasing 4. The free edges 26 of the filter bags are turned over sealingrings 28, band sewn together, and engage against the lands 30 betweenthe slots in front wall 24 and, of course, against the portions of thefront wall at the upper and lower ends of the slots and at the sides ofthe first and last slots as seen in FIG. 2. The sealing rings 28 areclamped against the aforementioned portions of the front wall by metalstrips 32 which support the respective clean air nozzles 16. In additionto clamping the'sealing rings 28 against the front wall of the casingadjacent the vertical slots, these strips 32 serve to close theotherwise open ends of the filter bags. Each metal strip 32 is securedby bolts 34 to the free ends of a U-frame 22, the shanks 36 of bolts 34threadedly engaging with nuts 38 secured within the free ends of thetubular U-frame 22. The strips 32 are forced towards the front wall 24of casing 4 by means of U bars which, in turn, are tightly engagedagainst the strips by means of clamp screws 42 whose inner endsthreadedly engage nuts 44 affixed on the inner sides of front casingwall 24.

When it is desired to replace or inspect a filter bag, this can easilybe done by unclamping U bars 40 and removing a filter unit whichconsists of a filter bag 20, the U frame 22 over which the bag isstretched and the meta] strip 32 which is bolted to the ends of the Uframe. The sealing rings 28 greatly reduce the likelihood that anyleakage around the free edges of the filter bags will occur; but, if anysuch leakage does occur, relatively clean air from the atmospheresurrounding casing 4 will be drawn into the filter pockets, rather thanthe dust-laden air which flows through the interior of casing 4.Conversely, if any leakage of dust laden air from within casing 4 occursaround the sealing rings 28, it will discharge into the atmospheresurrounding casing 4 rather than into a filter pocket 18.

in the following claims, where the terms dust-laden air" or clean air"are used, it will be understood that the terminology applies equallywell to gases other than air.

I claim: 1. A filtering device comprising a casing, means for feedingdust laden air to the interior of the casing, means at the bottom of thecasing for collecting dust, said casing having a wall with a pluralityof slots therein, a plurality of filter units insertable into andremovable from said casing through said slots, each comprising aU-frame,

a fabric filter bag stretched over the U-frame,

a strip having a clean air nozzle passage,

means securing the free ends of the U-frame to the strip,

said strip normally closing the open end of the filter bag and the freeedges of the bag engaging between the strip and the outer side of thecasing wall surrounding a slot,

and means for forcing said strips towards the outer side of said casingwall so as to clamp the free edges of said filter bags therebetween.

2. The combination claimed in claim 1, the means for forcing said stripstowards the outer side of the casing wall comprising a plurality of barsengaging across the strips, and clamp screw means engaging between saidbars and said casing wall.

3. The combination claimed in claim 1, the free edge of each filter bagbeing turned over a sealing ring which, together with said free edge, isclamped between a strip and said casing wall.

1. A filtering device comprising a casing, means for feeding dust ladenair to the interior of the casing, means at the bottom of the casing forcollecting dust, said casing having a wall with a plurality of slotstherein, a plurality of filter units insertable into and removable fromsaid casing through said slots, each comprising a U-frame, a fabricfilter bag stretched over the U-frame, a strip having a clean air nozzlepassage, means securing the free ends of the U-frame to the strip, saidstrip normally closing the open end of the filter bag and the free edgesof the bag engaging between the strip and the outer side of the casingwall surrounding a slot, and means for forcing said strips towards theouter side of said casing wall so as to clamp the free edges of saidfilter bags therebetween.
 2. The combination claimed in claim 1, themeans for forcing said strips towards the outer side of the casing wallcomprising a plurality of bars engaging across the strips, and clampscrew means engaging between said bars and said casing wall.
 3. Thecombination claimed in claim 1, the free edge of each filter bag beingturned over a sealing ring which, together with said free edge, isclamped between a strip and said casing wall.